[Bug 2166659] Re: Poweroff/reboot hang: deadlock between amdgpu_dm_ism_disable() and dm_ism_delayed_work_func (DCN 3.5, 100% reproducible)

Status changed to 'Confirmed' because the bug affects multiple users. ** Changed in: linux (Ubuntu) Status: New => Confirmed -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2166659 Title: Poweroff/reboot hang: deadlock between amdgpu_dm_ism_disable() and dm_ism_delayed_work_func (DCN 3.5, 100% reproducible) Status in linux package in Ubuntu: Confirmed Bug description: Laptop gets stuck on shutdown/reboot with screens off and status LEDs still on, power is not cut. Only hard power off (pressing the power button) makes it shut off completely. Shutdown reaches amdgpu_pci_shutdown → amdgpu_device_suspend → dm_suspend → amdgpu_dm_ism_disable(), which holds the ISM mutex while calling disable_delayed_work_sync(). The pending dm_ism_delayed_work_func (events_unbound) tries to take that same mutex and blocks: INFO: task kworker/u64:10:3985 is blocked on a mutex likely owned by task shutdown:1 hung_task fires after 120 s and panics (kernel.hung_task_panic=1). Looks like a lock/work-flush ordering problem in amdgpu_dm_ism_disable(): it flushes the work while holding the mutex the work acquires. 100% reproducible on every shutdown/reboot. Hardware: Lenovo 21WVCTO1WW, BIOS R38ET26W (1.06), DCN 3.5 iGPU, Secure Boot on (kernel lockdown). Kernel: 7.0.0-31-generic #31 (closed)-Ubuntu Tried amdgpu.dcdebugmask=0x10 — no effect. Workaround: modprobe -r / unbind amdgpu via a systemd ExecStop before shutdown → clean poweroff every time. Bug was also filed at https://gitlab.freedesktop.org/drm/amd/-/work_items/5776 ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-31-generic 7.0.0-31.31 ProcVersionSignature: Ubuntu 7.0.0-31.31-generic 7.0.14 Uname: Linux 7.0.0-31-generic x86_64 ApportVersion: 2.34.1-0ubuntu0.1 Architecture: amd64 CasperMD5CheckResult: unknown CurrentDesktop: KDE Date: Mon Sep 7 10:50:32 2026 InstallationDate: Installed on 2026-08-18 (20 days ago) InstallationMedia: Kubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423) MachineType: LENOVO 21WVCTO1WW ProcFB: 0 amdgpudrmfb ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-7.0.0-31-generic root=UUID=7b5d4157-6f6d-47c5-bccb-e34280bd732e ro quiet cryptdevice=UUID=b350f07e-7748-4391-bf8d-812bad18d36e:luks-b350f07e-7748-4391-bf8d-812bad18d36e root=/dev/mapper/luks-b350f07e-7748-4391-bf8d-812bad18d36e splash PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon. SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 06/03/2026 dmi.bios.release: 1.6 dmi.bios.vendor: LENOVO dmi.bios.version: R38ET26W (1.06 ) dmi.board.asset.tag: Not Available dmi.board.name: 21WVCTO1WW dmi.board.vendor: LENOVO dmi.board.version: SDK0T76576 WIN dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: None dmi.ec.firmware.release: 1.5 dmi.modalias: dmi:bvnLENOVO:bvrR38ET26W(1.06):bd06/03/2026:br1.6:efr1.5:svnLENOVO:pn21WVCTO1WW:pvrThinkPadT14Gen7:rvnLENOVO:rn21WVCTO1WW:rvrSDK0T76576WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_21WV_BU_Think_FM_ThinkPadT14Gen7:pfaThinkPadT14Gen7: dmi.product.family: ThinkPad T14 Gen 7 dmi.product.name: 21WVCTO1WW dmi.product.sku: LENOVO_MT_21WV_BU_Think_FM_ThinkPad T14 Gen 7 dmi.product.version: ThinkPad T14 Gen 7 dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2166659/+subscriptions